Messenger - Vol. 2, No. 1, Page 11
Fall 1992
Points of light guide Gait Lab
Using a computer linked to four video cameras, a University of
Delaware professor of physical education provides orthopedic surgeons
crucial information on how children with cerebral palsy walk.
In the Sports Science Laboratory adjacent to the University's ice
skating arenas in Newark, Jim Richards works with a biomedical engineer and
physical therapists from the A.I. du Pont Institute in Wilmington to
determine the velocity, cadence and stride of young subjects aged 4 to 21.
The Gait Lab computer compares how a child walks and runs with a range of
normal movement, and the results are coordinated with a electromyogram that
detects muscle activity.
A common crippling disorder of childhood, cerebral palsy is caused by
a non-hereditary brain abnormality and results in complete or partial
paralysis of the limbs. Sometimes, the limbs are completely immobile, or
they may simply be stiff and their movements weak or poorly controlled.
"The central nervous system is disordered and often causes muscles to
contract at inappropriate times," says Richards. "Sometimes, these children
have muscles that contract all the time. This puts stress on the developing
skeletal system, and so bones may grow abnormally in response to this
stress."
Physical therapy, braces and operations by orthopedic surgeons can
sometimes alter fixed stiffness in some limbs. The University's Gait Lab,
one of approximately 46 in the country, uses sophisticated computer
analysis to help doctors determine what techniques are best used to
alleviate particular problems, Richards says.
"We have two goals," says Freeman Miller, co-director of the cerebral
palsy clinic at A.I. du Pont Institute. "We evaluate the children to see
how they are walking prior to surgery and again afterward to see if the
surgery made the improvement we wanted or if other things should be done,
like bracing."
Seven or eight children are brought each month to the Gait Lab. The
entire evaluation takes three to four hours, during which the physical
therapist first mechanically measures the flexibility of the child's feet
and ankles and muscle resistance. Then the child is outfitted with highly
reflective gray balls at the ankle, the tibia (larger bone in the lower
leg) and the femur (thigh bone). Picking up these points of light from the
cameras, the computer plots them in a graph and creates a three-dimensional
view. Electrodes strapped on the limbs detect muscle activity.
The Gait Lab, now in its third year, will ultimately be duplicated at
A.I. du Pont Institute, Miller says. Collaboration with the University will
continue, however, as Richards develops new methods of measuring,
collecting, analyzing and displaying the data.
--Cornelia Weil